nherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes 74 of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the 75 phototransduction and, mutations in genes related to its metabolism are responsible for different retinal 76 dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4e5% of the retinitis 77 pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether phar- 78 macological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina 79 similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants 80 from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, 81 as determined by TUNEL assay. Western blot analysis and i...
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nherited retinal degenerations affecting both rod and cone photoreceptors constitute one of the causes 74 of incurable blindness in the developed world. Cyclic guanosine monophosphate (cGMP) is crucial in the 75 phototransduction and, mutations in genes related to its metabolism are responsible for different retinal 76 dystrophies. cGMP-degrading phosphodiesterase 6 (PDE6) mutations cause around 4e5% of the retinitis 77 pigmentosa, a rare form of retinal degeneration. The aim of this study was to evaluate whether phar- 78 macological PDE6 inhibition induced retinal degeneration in cone-enriched cultures of porcine retina 79 similar to that found in murine models. PDE6 inhibition was induced in cone-enriched retinal explants 80 from pigs by Zaprinast. PDE6 inhibition induced cGMP accumulation and triggered retinal degeneration, 81 as determined by TUNEL assay. Western blot analysis and immunostaining indicated that degeneration 82 was accompanied by caspase-3, calpain-2 activation and poly (ADP-ribose) accumulation. Oxidative stress 83 markers, total antioxidant capacity, thiobarbituric acid reactive substances (TBARS) and nitric oxide 84 measurements revealed the presence of oxidative damage. Elevated TNF-alpha and IL-6, as determined by enzyme immunoassay, were also found in cone-enriched retinal explants treated with Zaprinast. Our 85 study suggests that this ex vivo model of retinal degeneration in porcine retina could be an alternative 86 model for therapeutic research into the mechanisms of photoreceptor death in cone-related diseases, 87 thus replacing or reducing animal experiments.